Venturi siphon atomization liquid lift apparatus and method

ABSTRACT

A method and apparatus for increasing the production of a hydrocarbon well by removal of accumulated formation fluid from the bottom of the well. The apparatus includes a body positionable down hole and a sealing assembly, with a converging-diverging nozzle installed axially within a through bore extending through the body at a position below the sealing assembly. A fluid lift passage extends from the accumulated formation fluid through the body and into the throat of the nozzle. The entrance into the throat of the nozzle includes inwardly tapered shoulder portion position below the opening of the fluid lift passage into the throat. The apparatus creates a low-pressure zone within and lifts the accumulated formation fluid into the throat where it is atomized by a high velocity flowing production gas. The atomized fluid is carried to the surface of the well by the production gas where it is then separated from the gas. The method includes the installation of an apparatus within the well.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.60/743,691, filed Mar. 23, 2005, the entire of which is incorporatedherein by reference.

FIELD OF THE INVENTION

The present invention generally relates to an apparatus and a method forremoving formation fluids from the bottom section of hydrocarbonproducing wells. More specifically, an apparatus which uses the naturalflow of gases to enhance the production of hydrocarbons, such as gas,from a subsurface wellbore.

BACKGROUND OF THE INVENTION

It is common for a gas well to produce liquids in addition to gas. Theseliquids, typically termed as formation fluid, may include water, oil,and condensate. The accumulation of formation fluid in the well caneffect the flow characteristics of the well resulting in low productionor no production at all.

There exists several methods of removing or recovering the formationfluid from the well to simulate further production. A first methodremoves formation fluid from the well bottom by lifting it to thesurface using various pumps. A second method aims at maintaining gasvelocity at or above a critical velocity for production by continuallyreducing the diameter of the production tubing. A third method usesplungers which reciprocate in with in the well between the bottom whereformation fluid is capture by the plunger and the where the capturedfluid is unloaded. Another method includes artificial lift where apressurized fluid is injected into the well to increase gas velocity.

Despite the above and other methods and devices, a need still exists foran improved formation fluid lift and gas production device whichutilizes only the flow of produced gas to lift and atomize formationfluid for entrapment with produced gas to be carried to the wellsurface.

SUMMARY OF THE INVENTION

The apparatus of the present invention operates by using the naturalflow of well gases to remove accumulated formation fluid within a wellto increase production of the well and to avoid the use of artificialgas injection. In accordance with one aspect of the invention, there isprovided an apparatus for reducing the level of formation fluid at thebottom of a gas producing well including a narrowed throat section inwhich a production gas flow from the well creates a low pressure zonehaving a pressure less than the formation gas pressure. At least oneconduit provides a flow path from the formation fluid accumulated withinthe well to the low pressure zone.

The apparatus includes a body or mandrel run into a well casing usingconventional methods, or can be placed into a tubular and run into awell along with the tubular. The apparatus includes a sealing elementwhich seals against the well casing or tubular dividing the well casingor tubular into the top side region and the bottom side region. The bodyincludes a nozzle which creates a sufficient pressure difference betweenthe bottom side region and the top side region to provide for thelifting of formation fluid contained within the bottom side region, tocause the atomization of the formation fluid into small droplets whichare carried to the surface of the well by produced gas.

In general, in one aspect, an apparatus for lifting fluid from a wellusing the natural flow of well gases is provided. The apparatus includesa body being of dimension permitting the body to be lowered into a wellcasing, the body having a top section, a lower section and an outerwall. The body having an axial bore extending longitudinallytherethrough from a bottom side surface to a top side surface. The axialbore defining a converging-diverging nozzle having a throat sectionintermediate to and fluidically coupling the converging and divergingsections of the nozzle. A sealing element positionable between the outerwall of the body and the inner of the wall casing and sealing dividesthe well casing into a top side region and a bottom side region. Thebody having at least one aperture extending therethrough at a positionbelow the sealing element connecting together the bottom side region tothe throat section. The nozzle having a tapered shoulder extendinginwardly into the throat section and reducing the cross sectional areaof the throat section in a direction from the bottom side surface to thetop side surface. A tube having a first end connected to the at leastone aperture and a second end extendable into a column of formationfluid within the bottom side region.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be better understood and objects other than those setforth above will become apparent when consideration is given to thefollowing detailed description thereof. Such description makes referenceto the annexed drawings wherein:

FIG. 1 is a diagrammatic view of a venturi siphon atomization liquidlift apparatus constructed in accordance with the principles of thepresent invention positioned in a well bore about a bottom holelocation;

FIG. 2 is an enlarge cross sectional diagrammatic view of the venturisiphon atomization liquid lift apparatus showing an internalconverging-diverging nozzle configuration; and

FIG. 3 is an enlarge cross sectional diagrammatic view of theconverging-diverging nozzle showing an inwardly tapering portion.

The same reference numerals refer to the same parts throughout thevarious figures.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings, and particularly to FIGS. 1-3, apreferred embodiment of the venturi siphon atomization liquid liftapparatus of the present invention is shown and generally designated bythe reference numeral 10.

With reference to FIGS. 1-3, there is shown a diagrammatic partial viewof a well casing 100 positioned within a borehole 120 drilled into aformation 125. The venturi siphon atomization liquid lift apparatus(VSALL) 10 is shown positioned within the casing 100 at a bottom holelocation 110. It is important to note, the VSALL 10 can also be setwithin a tubular that is run into a well casing.

The VSALL 10 operates to increase gas production from the well bylifting accumulated formation fluid using only the transport velocity orenergy of the gas being produced. The VSALL 10 depends upon basic lawsof physics to lift the formation fluid to the surface.

In doing so, the VSALL 10 includes a body 12 of dimensions allowing thebody to be run in and positioned at the bottom hole location 110 usingconventional methods, such a wireline (not shown). The body 12 includesa top section 36, a lower section 38, and an outer wall 40. An axialbore 14 extends longitudinally through the entire length of the body 12along a central axis thereof from a top side surface 16 to a bottom sidesurface 18. The body 12 makes a sealing contact with an interior surface115 of the casing 110, thereby dividing the borehole into two regions, atop side region 130 and a bottom side region 140. The sealing contact iscreated by a sealing element 30 positioned around the circumference ofthe exterior surface of the body 12. The axial bore 14 establishes fluidcommunication between the top side region 130 and the bottom side region140, thereby permitting fluid to cross from the bottom side region tothe top side region by passing through the axial bore.

The axial bore 14 includes a nozzle 20 of a converging-divergingconfiguration. The nozzle 20 is orientated such that the convergingsection 22 is bottom side and the diverging section 24 is top side. Theconverging-diverging configuration of the nozzle 20 acts to increase thetransport velocity or energy of a fluid flowing through the body 12 fromthe bottom side region 140 of the borehole 100 to the top side region130.

The body 12 further includes at least one aperture 26 extending from thebottom side surface 18 to the throat 28 between the converging section22 and diverging section 24 of the nozzle 20. The throat 28 comprises anelongated narrowed section between the exit of the converging section 22and the entrance in to diverging section 24. Attached to and extendingfrom each aperture 26 is a lift tube 29. The lift tube 29 extends fromthe aperture 26 in a direction into the bottom side region 140 and intoformation fluid 150 that has accumulated within the borehole 120. Thelift tube 29 may be various lengths, dimensions, cross sectional shapeand may extend into the formation fluid 150 at various angles.

With reference to FIG. 3, at a lower stream end of the throat 28 justbefore the aperture 26 conjoins with the axial bore 14 at the throat,there is a narrowed section created by an inwardly protruding taperedshoulder 25. The shoulder 25 decreases the cross sectional area of thethroat in a direction from the bottom side surface 18 to the top sidesurface 16. The tapered shoulder 25 is formed annularly around the innerwall of the throat 28 with the top of the shoulder being flush with thelower edge of the opening of the aperture 26 into the throat, and normalto the inner wall of the throat. The reduced cross sectional area of thethroat 28 created by the tapered should 25 increases the transportvelocity of gas as it flows across the tapered shoulder. The gas flowingwith an increased transport velocity through the throat 28 and acrossthe end of the aperture 26 creates a low pressure zone. This lowpressure zone acts to siphon the formation fluid 150 up through the lifttube 29 and the aperture 26 into the throat 28. In the throat 28,formation fluid 150 flows across the top of the shoulder 25 into thenarrowed cross sectional area. The formation fluid 150 is atomized bythe high velocity gas into small droplets that are carried to thesurface of the well by the gas.

The VSALL 10 further includes a collar stop 32 either attached to thebody 12 or made integral therewith. Collar stops are well known in theindustry as such the specific details of the collar stop is not shown ordiscussed. The collar stop 32 fixedly attaches the body 12 of the VSALL10 to the casing 100 during run in using conventional methods. It iscontemplated that a tubing stop or an “A” packoff or some other suchfixing device could reasonably be used in place of the collar stop 32.

In use, it can now be understood, the VSALL 10 is run into the casing100 to a desired depth such that the lift tubes 29 are at leastpartially submerged into accumulated formation fluid 150. Upon reachingthe desired depth, the collar stop 32 is actuated fixing the body 12 ofthe VSALL 10 to the casing 100. Once the body 12 is fixedly attached tothe casing 110, the borehole 120 is divided into two regions, a top sideregion 130 and a bottom side region 140. All produced gas is forced toflow through the axial bore 14 and across the nozzle 20. Theconverging-diverging configuration of the nozzle 20 reduces the crosssectional fluid flow area of the borehole 120 resulting in an increasedcasing pressure within the bottom side region 140. The increased casingpressure within the bottom side region 140 causes produced gas to flowwith a higher velocity across the throat 28 of the nozzle 20, this isfurther enhanced by the tapered shoulder 25. The increased gas velocityacross the tapered shoulder 25 and through throat 28 creates a lowpressure within this region resulting in the siphoning of accumulatedformation fluid 150 by the lift tubes 29 into the throat. At the throat28, the gas is caused to expand rapidly as it enters the divergingsection of the 24 of the nozzle 20. The expanding gas atomizes siphonedformation fluid 150 entering the throat 28 and carries the atomizedformation fluid to the surface in tiny droplet form.

A number of embodiments of the present invention have been described.Nevertheless, it will be understood that various modifications may bemade without departing from the spirit and scope of the invention.

1. An apparatus for increasing hydrocarbon production from a well, theapparatus comprising: a body being of dimension permitting said body tobe lowered into a well casing, said body having a top section, a lowersection and an outer wall; said body having an axial bore extendinglongitudinally therethrough from a bottom side surface to a top sidesurface; said axial bore defining a converging-diverging nozzle having athroat section intermediate to and fluidically coupling the convergingand diverging sections of said nozzle; a sealing element positionablebetween said outer wall of said body and the inner of the wall casingsealing divides the well casing into a top side region and a bottom sideregion; said body having at least one aperture extending therethrough ata position below said sealing element connecting together said bottomside region to said throat section; said nozzle having a taperedshoulder extending inwardly into said throat section and reducing thecross sectional area of said throat section in a direction from saidbottom side surface to said top side surface; and a tube having a firstend connected to said at least one aperture and a second end extendableinto a column of formation fluid within said bottom side region.
 2. Theapparatus of claim 1, wherein said tapered shoulder gradually reducesthe cross section of said throat section in a direction from said bottomside surface to said top side surface.
 3. The apparatus of claim 2,wherein the top of said tapered should is flush with the bottom edge ofthe opening of said at least one aperture into said throat section. 4.The apparatus of claim 3, wherein said top of said tapered should isplaner and is normal to the annular wall of said throat section.
 5. Theapparatus of claim 1, wherein said sealing element is attached to saidbody at said top section.
 6. The apparatus of claim 1, furthercomprising: a stop collar positioned between said outer wall and theinner wall of the well casing to affixed said body to the well casing.7. The apparatus of claim 1, wherein said aperture extends through saidbody from said bottom side surface.
 8. A method for increasinghydrocarbon production from a well having accumulated formation fluid,the method comprising the steps of: positioning an apparatus down holeand forming a seal with the well to divide the well into a top sideregion and a bottom side region causing all produced hydrocarbons toflow through said apparatus from said bottom side region to said topside region; increasing the velocity of produced hydrocarbons flowingwithin said apparatus; creating a low pressure zone within saidapparatus by said increased velocity of produced hydrocarbon; deliveringformation fluid from said bottom side region to said low pressure zonewithin said apparatus; atomizing said formation fluid within saidapparatus within said low pressure zone into small droplets by saidincreased velocity of produced hydrocarbon; and lifting said smalldroplets upwardly to the surface of the well by said producedhydrocarbons.